Even if you take into account the price difference between 87 and diesel, you still spend less on fuel on the diesel variant. Let's not forget, with the 2.5 I5, it is pretty hard to maintain that combined expected 26 MPG rating, whereas the 34 combined for the diesel can be done by beating on the engine constantly. It is closer to higher 30s, whereas average values for the 2.5I5 are low 20s combined.

Show me who can get EPA estimates on gassier during normal driving.

From other hand if you read TDI forums there are complains that far amount of drivers cannot beat EPA estimates by more than 20% margin. (though some with magic break-in sequence are getting 45+ on highway@65mps or 47+mpg on country-roads @55mph)

Though I personally was getting during roundtrips to LA stable 38-39mpg (e.g. exact EPA estimates) while driving 80mph average and easy 42mpg if I keep myself at 65mph.